Normal_distributions

# Normal_distributions - Using Your TI-83/84 Calculator:...

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Using Your TI-83/84 Calculator: Normal Probability Distributions Elementary Statistics Dr. Laura Schultz Always start by drawing a sketch of the normal distribution that you are working with. Shade in the area (probability) that you are given or trying to find, and label the mean, standard deviation, lower bound, and upper bound that you are given or trying to find. Don't worry about making your drawing to scale; the purpose of the sketch is to get you thinking clearly about the problem you are trying to solve. For illustration purposes, let’s consider the distribution of adult scores on the Weschler IQ test. These IQ scores are normally distributed with μ = 100 and σ = 15 . Using the normalcdf command The normalcdf command is used for finding an area under the normal density curve. This area corresponds to the probability of randomly selecting a value between the specified lower and upper bounds. You can also interpret this area as the percentage of all values that fall between the two specified boundaries. 1. Let’s find the percentage of adults who score between 90 and 110 on the Weschler IQ test. Begin by sketching the distribution and labeling the relevant information. We are ultimately trying to find the area under the normal density curve that is bounded by 90 and 110, so shade in that area on your sketch. 2. Press `v for the = menu. Scroll down to 2:normalcdf( and then press e . 3.

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## This note was uploaded on 10/05/2008 for the course MA 120 taught by Professor Jerome during the Fall '07 term at Park.

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Normal_distributions - Using Your TI-83/84 Calculator:...

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